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34                                 ALASKAN GLACIER STUDIES
emerges from its broad mountain valley, then spreads out in a piedmont bulb reaching almost to the shores of Nunatak Fiord.
Just east of this piedmont bulb is the ice cliff of the tidal Nunatak Glacier whose history since first seen in 1891 up to 1910 was one of continued recession; but between August, 1909, and June, 1910, it advanced about 1000 feet. It has also a wasting land tongue, or distributary, and above its end hangs the Cascading Glacier, the type of a series of similar cascading glaciers in this region and elsewhere in Alaska. Opposite, on the north side of the fiord is Hanging Glacier which no longer cascades over its hanging valley lip. Hidden Glacier, to the southwest of Nunatak Glacier, was of peculiar interest in 1905 because the outwash gravel plain which separated its stagnant terminus from the sea rested for a distance on the glacier ice, which, by melting, gave rise to a pitted plain. All this is now destroyed, for when seen in 1909 Hidden Glacier was utterly transformed, having also undergone a spasmodic advance since last visited in 1906. The last glacier of the series studied in 1909-10 is Fourth Glacier, which terminates within its mountain valley, just back of the mountain front, being a typical valley glacier tongue of a through glacier system. It shows no sign of other recent change than that of recession.
Other names have been proposed for this glacier, notably Beasley Glacier, but we prefer the name Fourth Glacier, by which it is known locally, and because there seems no good reason for attempting to substitute another name. Besides being sanctioned by local usage, and by the United States Geographic Board, the term Fourth Glacier helps to record one of the bits of history of this region, as Malaspina, Haenke, Atrevida and other names record other historic events. In 1898-99 Yakutat Bay was visited by large numbers of prospectors who undertook to reach the reputed gold fields of the Alsek valley by an over-ice route, or else attempted to reach the Klondike district by an easier route than that over White Pass. Going up Yakutat Bay in boats they named the large glaciers in then; order, First (Turner), Second (Hubbard), Third (Nunatak), and Fourth Glacier, passing by Hidden Glacier, which perhaps they did not see, without naming it. Parties crossed by both the Third and Fourth Glacier routes. It is an interesting episode in the history of this region, and in tihe mining history of Alaska, and it is our belief that it is best to retain this one of the names that these adventurous prospectors applied to the region.
Former Expansion of the Yakutat Bay Glaciers. Throughout the entire Yakutat Bay region the evidence is complete that all the glaciers have at a former period been far more extended than at present.1 The period of greatest extension of the glaciers was recent in a geological sense, but was at least several centuries ago, for a mature forest grows on the deposits laid down by these expanded glaciers.
There are several lines of evidence upon which the conclusion is based that these glaciers were formerly far greater than now. In the first place, throughout the region the valleys show clear signs of pronounced glacial erosion. The valley walls are scored, grooved, polished and smoothed to elevations far above sea level, and, in those valleys in which glaciers still linger, to elevations far above the surfaces of the present glaciers. Tributary valleys hang above the level of Yakutat Bay, Disenchantment Bay, Russell
1 Tarr, R. S. and Martin, Lawrence, Glaciers and Glaciation of Yakutat Bay, AWW, Bull. Am. Geog. Soc., Vol. XXXVIQ, 1906, pp. 155-164. Tarr, E. S., The Yakutat Bay Region, Alaska, Professional Paper 84, U. S. Geol. Survey, 1909, pp. 96-137.